Houses are places for people to rest in, and are also safe places for people. Indoor safety of houses is very important for people's lives. A dangerous condition such as a fire may occur in a house, and if an alarm may be timely given, personal casualties and property loss may be reduced. Some equipment adopts a single fixed threshold value for alarm monitoring, the threshold value is proper in some scenarios, but in some scenarios, it may not be proper and easily cause the condition that an alarm is falsely given or not given.